The conditions presenting the need for this invention and for its development were discerned in the food processing industry. More particularly, those conditions were discerned in the context of machines used in breweries to apply paper-based labels and the like to filled bottles and the like. Depending upon the functions which they serve, the machines used to package beverages or foods can be subject to governmental regulations concerning cleanliness and are cleaned from time to time. The cleaning process typically includes spraying the machinery parts with water, containing a detergent, at high temperature (e.g., 150–160° F.) and pressure at 150 pounds psi, more or less. Under those circumstances, water enters into the gear boxes and other lubricated components of the machinery. Those machines have lubricating systems in which the normally clear lubricating oil is filtered and recycled.
Machines used to apply paper labels to filled beer bottles are called rotary labelers. Labelers typically include two stations called aggregates at which labels can be applied to a bottle. At each station there is a principle glue application roller to which a glue is applied. Glue is applied from that roller to the reverse side of a label via a transfer roller before the label is placed into contact with the bottle. The principle glue application and glue transfer rollers have vertical axes. The glue which typically is used is a non-Newtonian liquid which is substantially thixotropic in nature. The glue flows downwardly along the roller across the lower end of the roller and then down the roller's supporting shaft. The glue, because of its nature, passes through the seals associated with the roller shafts and thereby enters into the lubricated gear boxes of the labeling machines. The amount of glue which can enter into a given gear box can vary from small to very substantial, depending upon the tolerances of the machinery, its age, and particularly the condition of any seals which may be present on the roller drive shafts. The amount of glue present in a labeler gear box can be so great that when the labeler is shut down for a period, the glue can set adequately to prevent the machine from being restarted. It is apparent, therefore, that there is a need for a filter capable of removing glue from the lubricating oil in labeling machines used in the food processing industry, as well as in other labeling machines and in other contexts.
As noted above, machines used in the food processing industry are required to be maintained at specified cleanliness levels to prevent contamination of the food products. When those machines are periodically washed down as described above, water can also enter into the lubricating oil through the same seals through which the glue enters. When water is present in oil containing water soluble glue of the kind used in labelers in the food processing industry, the water dissolves the glue and causes the glue's adhesive to separate from a binder in the glue. The binder typically is talc or some other fine mineral powder present in the glue as a volumetric extender. Binder particles act as an abrasive to the lubricated machinery.